Control system



I Nov. 23, 1937. i s, A, MOREHQUSE 2,100,059

CONTROL SYSTEM Filed July 22, 1955 s Sheets-Sheec 1 Nov. 23, 193]. s. A. MOREHOUSE 2,100,059

CONTROL SYSTEM Filed July 22, 1955 3 Sheets-Sheet 2 ATTORNEY-5 Nov. 23, 1937. s. A. MOREHOUSE 2,100,059

CONTROL SYSTEM Filed July 22, 19:55 5 Sheets-Sheet 3 INVENTOR.

ATTORNEYS In N 1 Patented Nov. i 23, 193? CON Silas A. Moreno, Glendale, llaliit, at: to

Rocky Mountain Steel & fi -"1' Angelw,

Application my 22, less, seam No. 32.5%

This invention relates broadly to control systems for automatically maintaining two or more rotating devices at predetermined relative speeds and is particularly applicable to the control of engines in multi-engine airplanes, motor boats, and the like where the different engines are not connected to a common shaft but nevertheless should run at the same speed.

An object of the invention is toprovide a practicable mechanism for maintaining a plurality of engines in a predetermined desired speed relation.

A more specific object is to provide a mechanism of the type referred to which can be applied to airplanes, motor boats and the like and does not change the normal control or necessitate any attention onthe part of the operator.

Various more specific objects, features and advantages of the invention will be apparent from the following detailed description which refers to the drawings.

The system of the present invention has been designed for and successfully employed on airplanes and for that reason the specific application of the invention to an airplane will be described.

In the drawings:

Fig. 1 is a schematic diagram illustrating the application of the invention to the three engines of a tri-moto'r airplane;

Fig. 2 is a plan view of a preferred form of synchronizing' unit in accordance with the invention;

Figs. 3 and 4 are side and end views, respectively, of the device shown in Fig. 2;

Fig. 5 is a cross section through th mechanism shown in Fig. 2, the section being aken in the plane V-V of Fig. 2;

Fig. 6 is a cross section through the device shown in Fig. 2, the section being taken in the plane VI-VI of Fig. .2;'

Fig.7 is a sectional view taken at right angles to the section of Fig. 6 in the plane VII-VII of Fig. 6; and

Fig. 8 is a detail view of a safety link adapted to be inserted. in the linkage employed with my unit.

Fig. 9 is a detailed section in the plane IX-IX of Fig. 4.

Referring to Fig. 1, I have shown schematically three airplane engines A, B, and C, respectively,

all three of which are substantially identical and 7 each of which is provided with throttle valves la, 'lb, and 40, respectively, which control the supply of fuel to the engines, the speed of each engine being controlled by adjustment of the (es s) throttle valve. Each of the engines A, B, and C also has extending therefrom tachometer shafts he, so, and be, respectively, which are merely 'fiemble shafts connected to the rotary elements of the associated engines and adapted to rotate at all times in synchronism therewith. The throttle valves dd, lb, and 4c are provided with control rods ta, 6b, and 60, respectively, for opening and closi them, and other elements next to be described are employed for coupling each of the rods ts, db, and to to one of three throttle control levers id, lb, and lo, respectively, throttle la controlling engine A, throttle lb controlling engine B, and throttle l0 controlling engine 0. The three throttles la, lb, and is are, as is customary in airplane construction, positioned close together so that the operator can shift all three of them simultaneously if desired by grasping them all at once or he can shift them independently. A screw knob i2 is provided for locking the three throttles Ia, lb, and Iain any desired position to which they may have been moved.

As shown in Fig. l, throttle Ia which controls engine A is connected by a cable l8a passing over a pulley Me, a lever Ilia, a controlrod Mia and a bell crank lever l'la to the rod Ba associated with engine A so that movement of the throttle la is positively transmitted to the rod 60.. A

spring 88a may be provided to maintain the cable w 63a taut.

Throttle lb is similarly connected by a cable I322 passing over a pulley Mb, a lever i511, a rod Nb and a bell crank lever 61b to the throttle rod 3b associated with the engine B. Throttle lc is likewise similarly connected by a cable I30 passing over a pulley Me, a lever I50, a rod I60 and a bell crank lever l'lc with the throttle rod 60 associated with engine C.

The bell crank lever He has a fixed fulcrum so that the throttle valve 40 is positively and solely responsive to movements of the throttle lc associated with that engine. Engine C therefore functions as a master engine which determines the speeds oi the other engines A and B, respectively.

To automatically regulate the speeds of engines A and B with respect to each other and with respect to engine C, the fulcrums of the bell crank levers Ma and Nb are adapted to be shifted, and similar mechanisms 20a and 2017 are provided for automatically shifting the fulcrums of the associated levers, the mechanisms 20 and 20b being operated from the tachometer shafts 5a, 5b, and 5c in a manner next to be described. Y The tachometer shaft 5b extending from engine B is connected to both mechanism 28a and mechanism 28b. Thus, as shown, shaft 55 is extended directly to a take-out 22 from which an auxiliary tachometer shaft 5b extends to the mechanism The construction and operation of the mechanisms 28a and 28b will be described in detail later. It will suffice to sayv at this point that each of the mechanisms 28a and 28b functions in response to a difference in the speeds of the two tachometer shafts connected thereto to shift the fulcrum of the associated bell crank lever Ila or |'|b upwardly or downwardly to shift the associated throttle rod 6a or 6b and open or close the throttle without shifting the associated throttle 1a, or 1b.

Referring now to Figs. 2 to 7, inclusive, each of the units 28a and 281) comprises a casing 25 having rotatably mounted therewithin a shaft 26. Thus as shown, shaft 26 is mounted in bearing bushings 21 in opposite walls of the casing. The shaft 26 has keyed thereto a gear 28 and a differential hub 29. The gear 28 is provided with a hub 38 having a set screw 3| therein for locking it to shaft 26. The differential hub 29 likewise has a set screw 32 therein for locking it to shaft 26 after the parts have been assembled toanism of well known type.

gether. Rotatably mounted upon shaft 26 on opposite sides of the hub 29 are a pair of worm wheels 33 and 34, respectively, each of which has secured thereto a bevel gear 35 and 36, respectively, which bevel gears mesh with bevel gears 31 and 38, respectively, mounted for rotation about their axes on the hub 29 by screws 39, the gears 35, 36, 31, and 38 constituting a differential mech- The worm wheel 33 meshes with a worm 48 mounted on a shaft 4| which is rotatably supported at opposite ends in bushings 42 in the casing 25.

One end of shaft 4| projects through its associated bushing 42 and is provided with a squared end 43 adapted to engage a square socket 44 on the end of a tachometer shaft designated generically by the reference numeral 45 which may correspond'to any one of the tachometer shafts 5a, 5b, 50 or 5b shown in Fig. 1. A conventional connection 46 may be employed to secure the housing of the tachometer shaft to the casing 25.

The worm wheel 34 engages a worm 48' mounted on a shaft 4|, mounted in bushings 42' in the housing 25. This shaft 4| is also provided with a squared end which projects, however, from the opposite end of the housing 25 to that from which the shaft 4| projects, this arrangement being clearly shown in Fig. 2. The purpose of bringing the shafts 41 and 4|, respectively, out'of the casing- 25 on opposite ends thereof is to cause the worm wheels 33 and 34 to be driven in opposite directions when their associated shafts 4| and 4| are connected to tachometer shafts rotating in the same direction. It will be obvious that if the worm wheels 33 and '34 are rotated in opposite directions at equal speeds, the differential gears- 3| and 38 willsimply rotate about their pivot screws 39 and no rotation of hub 29 and shaft 26 will occur. However, should the wheels. 33 and 34 be rotating in opposite directions at difierent speeds, then a differential motion will be'transmitted to the shaft 26, which differential motion is used in a manner to be described to control the speeds of the engines.

The gear 28 meshes with a gear 58 locked to a shaft 5| which is rotatably mounted in bushings 52 in the housing 25. The shaft 5| also has locked thereto for rotation therewith a bevel gear 54 which meshes with 'a bevel gear 55 locked to a shaft 56 which is rotatably mounted and projects through a bushing 51 anchored in the wall of the casing 25, the shaft 56 having on its outer end an eccentric stub shaft 58 which constitutes the pivotal mounting for the bell crank levers Fla and Ill).

The operation of the mechanism 28a to correct adiscrepancy in speed between the two motors, the tachometer shafts of which are connected to that mechanism, will now be apparent. Thus any difference in the speeds of the two tachometer shafts will cause the worm gears 33 and 34 to travel in opposite directions at different speeds which will result in a slow rotation of the differential hub 29 and shaft 26. This in turn rotates the gear 28 which rotates the gear seg ment 58, the latter rotating the shaft 5| and gear 54, which in turn rotates gear 55 and shaft 56 to raise or lower the eccentric stub shaft 58,

thereby raising or lowering as a unit the bell crank lever 28a or 28b mounted on that unit and opening or closing the associated throttle 4a or 4b to increase or decrease the speed of the associated engine. Obviously the initial orientation of the stub shaft 58 must be such-as to produce a compensating effect, i. e., close the throttle of the engine, the tachometer shaft of which is rotating at too high a speed.

Referring back to Fig. 1, it will be observed I that the two worm shafts of the mechanism 28b are connected by tachometer shafts 5c and.5b and 5b, respectively, to engines C and B so that the mechanism 28b functions to bring the engine B into synchronism with engine C. Likewise the mechanism 28a has its two worm shafts connected through tachometer shafts 5b and 5a, respectively, to engines B and A, thereby functioning to bring engine A into synchronism with engine B. Obviously, if desired, engine A could be controlled directly with respect to engine C by connecting the one worm shaft of mechanism 28a to tachometer shaft 50 instead of 5b.

It is common in airplane practice to frequently, either unintentionally or intentionally, run one engine at a radically different speed from another for a period, as when testing. Therefore if special means were not provided to prevent such action, the gear segment 58 would quickly run out of mesh with the gear 28 and the device would be inoperative. To prevent such occurrence, spring stops are provided for limiting motion of the gear segment 58. These stops comprise a pair of spring detents 68 and iL-respectively, which engage the radial edges 62 and 63 of the gear segment 58 just before the latter passes out of mesh with the gear 28. This does not prevent the segment from passing out of mesh with gear- 28. but resiliently urges the gear segment back into mesh so that normal driving relation between gear-23 and the segment 58 is reestablished'as soon asthe direction of gear 28 is reversed. However, as long as the gear 28rotates in a, direction tending to force the segment 62 against one of the stops 68 or 6|, the teeth of the gear28 merely click against the last teeth on the segment 58. The arrangement describedmakes it impossible to in any way damage the automatic synchronizing equipment by independently rotating one of the engines at a different speed from the others.

If the throttles Ia. and lb have a full range of motion just sufficient to completely open and close the associated throttle valves 40., and 4b when the automatic control mechanism is in neutral position, then when the latter is out of neutral position the range of motion of the associated throttle might be limited and if the operator attempted to shift the throttle to the end of its normal range severe strains would be imposed upon the linkage connecting the throttle to its associated throttle valve. To prevent such strains, I prefer to insert in each of the rods Ito and Nib a resilient lost motion device 10 which I isillustrated in detail in Fig. 8. Thus it comprises a sleeve member 1| connected at one end by'a clevis pin 12 to the rod "a and adapted to receive within its hollow body a plunger 13 on the end of a rod 14, which in turn is attached by a .turn buckle l and clevis pin 16 to the end of the other section of the rod lia. The rod 14 passes through a bushing 11 threaded into the sleeve H and the plunger I3 is positioned between a pair of helical springs 18 and 19 mounted within the hollow portion of the sleeve II, the opposite ends of the springs bearing against the inner end of the hollow portion of the body II and against the bushing 11, respectively. The springs 18 and 19 are sufficiently stifl to normally transmit all movement of the associated throttle la or lb to the associated bell crank lever Ila or III) while pemiitting lost motion and further movement of the associated throttle when the bell crank lever hasreached the limit of its motion.

Although the invention has been described in detail with reference to two types of airplanes, the application of the essential principles of the invention to other multi-engine planes having any number of engines or to motor boats and other devices containing engines to be synchronized, will be obvious to those skilled in the art, and the invention is therefore to be limited only as set forth in the appended claims.

I claim:

1. In combination with two independently driven shafts to be synchronized, control means for varying the speed of one of said shafts, differential means connected to said two shafts comprising a differential member rotatable in response to a departure from a predetermined speed relation between said shafts, a rotatable driving member coupled to said differential member for rotation thereby, an oscillatable driven member in driven relation with said driving member only through a predetermined arc of oscillation of said driven member, the latter moving out of driven relation with said driving member .in response to movement beyond the said arc, means operable in response to oscillation of said driven member beyond said arc for resiliently urging said driven member back into driven relation with said driving member, and means for actuating said control means in response to movement of said driven member within said arc. I

2. Means as described in claim 1, in which said driven member hasa segmental contact face for contactingsaid driving member.

3. Means as described in claim 1, in which said means for resiliently urging said driven member back into driven relation with said driving member comprises spring stop means engageable with said driven member as the latter approaches the ends of its arc of movement.

4. Means as described in claim 1, in which said driving and driven members consist of a gear and a gear segment, respectively.

5. In combination with two rotary devices to be synchronized, one of which comprises a throttle-controlled engine, a throttle therefor, differential means connected to said two devices comprising a differential member rotatable in response to a departure from a predetermined speed relation between said devices, a rotatable driving member coupled to said differential member for rotation thereby, an oscillatable driven member in driven relation with said driving member only through a predetermined arc of' lation with said driving member, control means for selectively setting said throttle at any desired opening, and means operable with said control means in any desired position for varying said throttle automatically in response to rotation of said driven member within said arc.

6. In combination with two rotary devices to be synchronized, one of which is a throttle-controlled engine, differential means coupled to said devices and comprising a shaft rotatable in response to a difference in the speeds of I rotation of said devices, manual throttle control means, means connecting said control means to the throttle of said engine comprising a bell crank lever haying two arms with links connecting one of said arms to said control means and connecting the other arm to said throttle, pivot means for oscillatably supporting said bell crank lever, and means for shifting said pivot means in response to rotation of said shaft.

'7. Means as described in claim 6, with a resilient lost motion means incorporated in said first linkage means.

SILAS A. MOREHOUSE. 

